1Image courtesy of Earth Sciences and Image Analysis Laboratory, NASA Johnson Space Center.2 Earth is wrapped in a thin blanket of air. We call it the atmosphere. Earth's atmosphere is a mixture of gases. It is special because it has oxygen. Some planets have atmospheres that are full of poisonous gases, but not Earth's! People and animals on Earth need oxygen to breathe. Some of our atmosphere is carbon dioxide. Plants need carbon dioxide to live. Ozone is another gas found in the atmosphere. There is more nitrogen gas in our atmosphere than any other kind. We don't need it, but more importantly, it doesn't hurt us.